a = [47, 18]
b = [49, 19]
c = [48, 18]
d = [44, 19]
e = [42, 17]
l1 = [a, d]
l2 = [c, d, b]
l3 = [e, a, c]
multi1 = [l1, l2, l3]

centerL1 = [ l1[0][0] + l1[1][0] / 2.0, l1[0][1] + l1[1][1] / 2.0 ]

print centerL1